In LEGION Simulator, with a LEGION Simulation File open, there is an option on the Playback menu called 'Simulation Seed'. The 'seed' is used to start the sequence of calculations made by the software during a simulation (such calculations govern the preferred speed of Entities, their size, and how they make decisions within the course of a simulation). This option enables a simulation to run using either a new series of calculations or the exact same calculations used in a previous simulation.

Using the same seed as a previous simulation can be useful in many situations, for instance:

• Problems or errors in a playback that need to either study the problem area more closely in the next playback
• Adjustment to model geometry to see whether such changes make a difference when the same seed is used.

To aid seed selection, the number of the current seed is now displayed in the Output Bar of LEGION Simulator, for example: "Simulator is using seed 772736266"

To use the Simulation Seed option:

1. Open a LEGION Simulator File.
   • The number of the seed to be used in the next playback is displayed in the Output Bar.
2. Play back the simulation one or more times as required, selecting Playback > Restart to return the simulation to its start time.
   Note: Each time simulation restarts, a new seed number is generated and displayed in the Output Bar. Only specify a particular seed when a simulation must be repeated exactly; until then, each seed will be randomly generated.
3. To specify a particular seed, select Playback > Simulation Seed.
   • The ‘Simulation Seed’ dialog is displayed.
     
4. Select the Use seed option.
5. Enter the number of the seed to use again in the edit box (check the Output Bar for seed numbers).
6. Click OK.
7. Play back the simulation again.
   • The simulation will now use this seed every time it runs.
8. To revert to using a random seed, repeat steps 3 to 6 but select the Use random seed option.

This will cause the seed to change each time simulation is restarted.